Support Actionable Diagnostics from Scala 2.13.12+

[saeltz]

Scala 2.13.12 added actionable diagnostics to the compiler and and info/warning/error messages.
We needed to change our tests in #789 to accommodate that change.
In future versions of Scapegoat, we could also support the actionable diagnostics in a way that we suggest a fix for rules where it makes sense.
An example: AvoidToMinusOne inspection would automatically suggest to rewrite x to n-1 to x until n.

Discuss: This would not work for older Scala versions. So we either only support Scapegoat for newer Scala versions or somehow create an internal intermediate model that maps to the Scala version's info message.

[domdorn]

is this required to get an initial release for scala 2.13.12 ? from what I got from this ticket, this is additional functionality?

[saeltz]

is this required to get an initial release for scala 2.13.12 ?

No.

from what I got from this ticket, this is additional functionality?

Yes.